ODOT workers uncover ancient past with future implications

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»Play VideoThese are some of the trees that ODOT workers discovered preserved in an ancient landslide. Carbon dating found they are between 50,000 and 60,000 years old.

PORTLAND, Ore. - State workers have uncovered the remnants of the region’s ancient past along an Oregon highway project that could shed light on what the Northwest looked like before the ice age and what disasters may lie ahead.

Oregon Department of Transportation workers discovered trees at least 50,000 years old that were buried 150 feet below ground during an ancient landslide. They found the pieces while digging into hillsides near Eddyville along Highway 20.

The trees, some of them currently resting in ODOT’s Corvallis yard, were encased in clay during a debris flow tens of thousands of years before the last ice age. Project Manager Joe Squire, who’s not only an engineer but also a geologist, knew the trees were significant as soon as they were unearthed.

“They were cedar logs and they had bark on them. They had root wads on them. There were small branches,” he said. “You don’t see well-preserved wood 150 feet below grade too often, and when you do, you have to imagine, how did it get there?”

With his geological background and knowledge of earth movements in the area, Squire knew it had to be a major ancient slide.

“It was probably a brutal day out here (when the landslide happened) if you were a deer or an elk and it takes down the forest and the trees and the whole works,” he said.

Squire began snapping pictures of the find and immediately got scientists at Oregon State University, the University of Arizona and Fresno State onboard. Carbon dating proved the trees were between 50,000 and 60,000 years old.

Those dates are important to Portland State University geologist Scott Burns, an authority on landslides and debris flows.

“That gives us the date when the tree died and then it is telling us when that particular landslide probably occurred,” he said.

Burns said it’s another piece to the puzzle for geologists studying not only these devastating events but also the giant historical earthquakes which have occurred along the coastline.

“We can put together a record and see how often these big earthquakes occur,” he said. “And so if we can get them over the last 50,000 years, then we can say this is what happened in the past and this will be the recurrence interval for the future.”

It gives scientists an idea of when the region can expect a major tsunami like the one that nearly wiped out Sumatra. Coincidentally, the very highway project where the discovery was made will serve as an escape route for tsunami survivors when the Big One hits here.

In addition to the trees, Squire said boulders the size of suburbans where also found. “It’s not layered at all. It’s just a jumble of material,” he said.

The nature of the slide also preserved pine cones with seeds, bark, roots, pollen and possibly fossilized insect remains.

The scientists studying the trees said that not only will they help them and others understand what the earth was like when the slide occurred but it may also tell them what can be expected if global warming continues. They hope the trees will help explain how plant life will respond and what that could mean for the future of humanity.

There have only been three other discoveries like this in the world. One was on the Oregon Coast and the other two were in Chile and New Zealand.